Is there anyone else who notices that their fuel pressure drops when the grid heater kicks in? It only drops about 1-2 psi. I thought that is might be the filters but I changed them. What else could it be? Gauge is accurate and post filter.

 

I've noticed that my FP comes up several psi once the engine is up to a good operating temp. Makes me wonder if the grid heaters are pulling enough juice to slow the LP down. Anyone know when the grid heaters cut off completely?

 

do you have an electric or manual gauge?

I thought the heaters stopped at 60 *F or anything over 20-25mph....

 

Yes, I have noticed the FP drop with the volt meter when the grid heaters cycle on. It is an eletric gauge.

 

Maybe a function of the ECM/PCM? When the heater comes on, the engine calls for more power, thus the fuel pressure drops. Just like slight acceleration will cause the fp to drop a little.

 

Normal because the batterys voltage drop due to the 200 amp load the grid heaters take.

 

I haven't noticed a pressure drop but I put in a FASS pump that has a definite distinctive sound and it changes as the grids cycle.
If you are losing pressure then your pump is probably at capacity so keep an eye on it, that or your batteries are on the way out.

 

I have a mechanical gauge. I thought that it might have something to do with the batteries but the cold weather has put them to the test. I know that my batteries are still good if they can start in -20 w/o the windchill.

 

My FP drops 1-2psi when the heater grids cycle, and my lights dim, and my dash dims, etc. Seems normal.

 

I just wanted to make sure that it wasn't the pump gong bad or something.

 

Ditto, the gearotor definately slows a bit and changes pitch...but no loss of FP!

RJ

 

I notice a drop of a couple psi from 25 to about 23 when the grid heaters are cycling. perfectly normal and to be expected when there is a 200 amp draw on the batteries... less voltage to the fuel pump less = pump speed= less pressure. some pumps will not notice this if they have automatic returns or bypasses... even though the pump is still spinning slower and pushing less fuel when the grid headers are on the pump is just going to bypass less fuel and show a constant pressure on the gauge... no big deal, like others have said normal

 

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Some trucks are more noticable than others......

The grid heater only works when IAT temps are below a certian degree....like 50*F or something like that. And they cut off over 20 MPH for some reason....guess they figure EGT will be high enough to take over.

I wouldnt worry about it. As long as the pressure comes back up when the heaters are off....you are fine....

Might not hurt to load test the batts and check the Alt for diode funciton though.....most NAPA's and such have a high end batt/alt tester that work pretty good...just make sure they test one at a time!